A relatively small number of Chinese characters known as : ; : do not have a one-to-one mapping between their simplified and traditional forms. This is because the simplification process merged two or more distinct characters into one. In most cases, the characters all have the same pronunciation, but their meanings may be completely unrelated.

As a result, converting text from simplified to traditional characters is difficult to automate, especially in the case of common characters such as (behind, empress), (table, clock), (traitor, rape) and more.

By far less common are traditional characters that map to two simplified characters.

The following is an exhaustive list of all characters whose simplified and traditional forms do not map in a one-to-one manner. Simplified characters are marked with a background, and traditional characters with .

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1 to 3

　
　
　
　
　
　
　
　
　
　

　
　
　
　
　

1 to 4

　
　
　
　
　
　
　

1 to 5

　

2 to 1

　
　
　
　
　
　
　
　
　
　
　
　
　

Special Case

薴(níng) (limonene Limonene Limonene is a colourless liquid hydrocarbon classified as a cyclic terpene. The more common D isomer possesses a strong smell of oranges. It is used in chemical synthesis as a precursor to carvone and as a renewably-based solvent in cleaning products.... ) has the simplified form 苧；however 苧(zhù) (a type of grass) is a traditional character, which has the simplified form 苎.